When the Centre of Newton ring is bright?

When the Centre of Newton ring is bright?

A bright centre in reflected system can be obtained by selecting lens, medium and the glass plate in such a way that refractive index of lens is less than the medium and refractive index of medium is less than the plate. That means μ1 < μ < μ2.

When Newton rings are seen through the transmitted light then the central spot is?

2 (III). If Newton’s rings are observed in the transmitted light, the interference pattern is complementary to that in the reflected light. The centre of the set of circles is bright in the transmitted light. Therefore the bright rings are measured instead of the dark ones.

Why do we use monochromatic light in Newton Ring experiment?

The interference pattern can be observed clearly when monochromatic light is used. When white light is used the interference pattern will not be very clear because different wavelengths of light interfere at a different thickness.

Why are the fringes circular in Newton rings?

4.In a newtons ring set up the air film is enclosed below the convex lens. The thickness of the film is constant over a circle (or concentric circles) having center at the center of the lens. Hence the fringes are circular.

Do you get Newton’s rings in transmitted light?

3.3. 2, the Newton’s rings are studied both in reflection and in transmitted light. As the partial beams in the air wedge are shifted in phase by λ/2 for each reflection at the glass surfaces, the interference conditions for reflection and transmitted light are complementary.

Why is monochromatic light used?

Simply put, light with the same wavelength will only show a single color and will be monochromatic. When using monochromatic light, the interference pattern is visible. Because different wavelengths of light interfere at different thicknesses when white light is used, the interference pattern is not very clear.

Why is the centre of the interference pattern dark?

Why Newtons Rings are circular and centre of interference pattern is dark? The path difference between the reflected ray and incident ray depends upon the thickness of the air gap between lens and the base. Thus incident ray and reflected ray interfere destructively. Hence, centre of interference pattern is dark.

Why is the central fringe white?

Answer White light consists of waves of innumerable wavelengths ranging from violet to red color. So if monochromatic light in Young’s double-slit experiment is replaced by white light, then the waves of every wavelength form their separate interference patterns. So the central fringe is white.

Why is the centre of Newton’s rings is dark?

The area just around the contact point is giving interference fringes, and they have air between them, but the path difference of interfering rays is still very close to zero, hence the dark fringe. Moreover, there is often a miniscule dirt or particle at the point of contact, so the plates are not exactly touching anymore.

Why is there a dark spot at the centre?

Leading to a net phase reversal & cancelation at the centre, where path length is zero, hence we observe a dark spot at the centre. On a side note, this condition also applies when the setup is done under water, but since the wavelength of the incident light (now) will be shorter, the rings (fringe pattern) will be more closely spaced.

Where is the interference path in Newton’s rings?

Explain. The Newton’s rings experiment shows interference rings between a flat surface and a spherical surface sitting on top of it. The interference path is the gap in between the sphere and the plane. The center is where the curve of the sphere is touching the plane.

Why are the fringes of the light bright and dark?

As explained in the above mentioned thread, the bright and dark fringes are because of constructive and destructive interference respectively due to the difference in path length traversed by the interfering light rays.